The present invention relates to the general field of quality-control inspection of the profile of cylindrical rollers used in roller bearings for a turbomachine.
Rolling bearings are commonly used in the field of aviation. In a turbomachine, rolling bearings are used in particular to support a first shaft to rotate relative to a second shaft that is coaxial about the first. Such bearings are constituted essentially by balls or cylindrical rollers held in raceways formed in outer and inner rings. In general, in a turbomachine, ball bearings are used for retaining axial loads and roller bearings are used for retaining radial loads.
The rolling bearings used in a turbomachine, and in particular those having cylindrical rollers, are subjected to numerous mechanical stressed. Although the number of failures observed is quite low, it has nevertheless become necessary to improve the reliability of rolling bearings and in particular by checking the profile of such rollers. Inspecting a cylindrical bearing roller for reliability involves in particular analyzing the general profile of the roller. Such analysis can be performed using standard instruments for measuring shape and area, such as roughness measuring machines fitted with an inductive sensor using a diamond or a laser, for example.
In practice, cylindrical bearing rollers are tapered at their ends in order to avoid excess edge stresses. The connection zones between the two tapers and the cylindrical portion of a roller can also lead to contact stresses that are unacceptable in terms of roller reliability. Unfortunately, standard measurement equipment does not make it possible to inspect these connection zones. Most such instruments are restricted to measuring profiles that are simple and single (such as profiles that are plane, circular, spherical, or cylindrical) and they do not provide a reliable manner for processing profiles comprising a combination of simple profiles of the kind associated with connection zones between the tapers and the cylindrical portion of a roller. Thus, checking a cylindrical bearing roller for reliability does not include any requirement about such connection zones.